Odds

Betting odds are written in the form $r:s$ (``$r$ to $s$'') and correspond to the probability of winning $P=s/(r+s)$. Therefore, given a probability $P$, the odds of winning are $(1/P)-1:1$.

See also Fraction, Ratio, Rational Number

References

Kraitchik, M. ``The Horses.'' §6.17 in Mathematical Recreations. New York: W. W. Norton, pp. 134-135, 1942.